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United States Patent |
6,128,943
|
Lemmens
|
October 10, 2000
|
Adjustment mechanism for hand tools
Abstract
The present invention is an adjustment mechanism for both hand and
production tools of any capacity. An eccentric pin mechanism provides the
pivot between two handles or other load transferring members. The rotation
of the pin moves the two members closer or farther apart, indirectly
controlling the final position of the blades or jaws. This adjustment can
be used to compensate for wear or to provide adjustment for a specific
use. The eccentric pin is locked into position by means of a pressure pin
mechanism. For light duty tools, this pressure pin mechanism would consist
of a spring loaded pin which resists rotation of the eccentric pin during
normal operation of the tool. The spring loaded pin would allow rotation
of the eccentric pin when a tool is used to rotate it. For heavy duty
applications, the pressure pin mechanism would consist of a solid set
screw. This set screw would be loosened before rotation of the eccentric
pin, and then tightened after adjustment to prevent rotation of the pin
during normal use. Rotation of the eccentric pin can be performed with
various hand tools. A handwheel or lever could be used for certain
applications which would require rapid adjustment of the tool. This
handwheel or lever would allow adjustment of the eccentric pin without the
use of tools. In this situation, a second eccentric pin could be located
at another pivot point to provide additional adjustment.
Inventors:
|
Lemmens; Joseph R. (910 S. Salem St., Apex, NC 27502)
|
Appl. No.:
|
314502 |
Filed:
|
May 19, 1999 |
Current U.S. Class: |
72/409.01; 30/192; 81/385; 81/387; 81/416 |
Intern'l Class: |
B21D 007/06 |
Field of Search: |
72/409.01,409.12,409.1
81/416,385,393,386,387
30/192,191,259
|
References Cited
U.S. Patent Documents
584191 | Jun., 1897 | Porter | 81/387.
|
2926556 | Mar., 1960 | Dupre | 72/409.
|
5012666 | May., 1991 | Chen | 81/382.
|
5842371 | Dec., 1998 | Liaw | 72/409.
|
Foreign Patent Documents |
1150500 | Aug., 1957 | FR | 81/385.
|
916411 | Jan., 1963 | GB | 81/416.
|
Primary Examiner: Crane; Daniel C.
Parent Case Text
This application claims benefit of provisional application Ser. No.
60/086,310 filed May 21, 1998.
Claims
What is claimed is:
1. An adjustable mechanism for tools having at least one moveable blade or
jaw including a load transferring means securing the moveable members
together, at least one moveable handle to transfer power to the tool, said
adjustable mechanism comprising:
a) an eccentric pivot pin having an eccentric circular cross section in the
middle of said eccentric pivot pin and having an inline circular cross
section at one end, said eccentric pivot pin having an enlarged head with
a plurality of circumferentially extending detents formed thereon at an
opposed end, said eccentric circular cross section contacting a first load
transferring member, said inline circular cross section contacting a
second load transferring member,
b) a locking means securing said eccentric pivot pin from moving axially,
c) a pressure means comprising a longitudinally extending member mounted
radially with respect to a longitudinal axis of said pivot pin and being
designed to exert a force on one of said detents on said pivot pin head
whereby said eccentric pivot pin is prevented from rotating during normal
operation of said tool,
d) a control means on one end of said eccentric pivot pin whereby rotation
of said control means rotates said eccentric pivot pin.
2. The adjustable mechanism of claim 1 wherein said eccentric pivot pin
head is of polygonal shape with rounded corners.
3. The adjustable mechanism of claim 2 wherein said power transfer member
contains markings showing the successive positions of said eccentric pivot
pin whereby the position of said blade or jaw can be adjusted from one
extreme to another.
4. The adjustable mechanism of claim 3 wherein said locking means is a
spring clip or locking pin.
5. The adjustable mechanism of claim 3 wherein said control means contains
a hexagonal hole for adjustment with a hex wrench.
6. The adjustable mechanism of claim 3 wherein said control means contains
a hexagonal head for adjustment with a wrench.
7. The adjustable mechanism of claim 3 wherein said control means contains
a control lever to allow hand adjustment.
8. The adjustable mechanism of claim 3 wherein said control means contains
a handwheel to allow hand adjustment.
9. The adjustable mechanism of claim 3 wherein said pressure means is an
elastic member which flexes during adjustment of said eccentric pivot pin
but provides adequate pressure to prevent rotation of said eccentric pivot
pin during normal use of said tool.
10. The adjustable mechanism of claim 3 wherein said pressure means is an
adjustable spring loaded pin.
11. The adjustable mechanism of claim 3 wherein said pressure means is a
locking screw.
12. The adjustable mechanism of claim 3 wherein said eccentric pivot pin is
located at the pivot between said blade or jaw and said load transferring
member.
13. The adjustable mechanism of claim 3 wherein said eccentric pivot pin is
located at the pivot between said handle and said blade or jaw.
14. The adjustable mechanism of claim 3 wherein said eccentric pivot pin is
located at the pivot between said handle and a second handle.
15. The adjustable mechanism of claim 3 wherein said eccentric pivot pin is
located at a pivot connecting a table-mounted member of said tool to a
member of said tool which moves relative to said table-mounted member.
16. The adjustable mechanism of claim 3 wherein a second eccentric pivot
pin is located at a second pivot point, whereby additional adjustment of
said blade or jaw is possible.
17. A hand tool having first and second handles with said first handle
being moveable and having at least one moveable blade or jaw including a
load transferring means securing the moveable members together, and an
adjustable mechanism connecting said handles, said adjustable mechanism
comprising:
a) an eccentric pivot pin having an eccentric circular cross section in the
middle of said eccentric pivot pin and having an inline circular cross
section at one end, said eccentric pivot pin having an enlarged head with
a plurality of detents thereon at the other end, said eccentric circular
cross section contacting a first load transferring member, said inline
circular cross section contacting a second load transferring member,
b) a locking means securing said eccentric pivot pin from moving axially,
c) a pressure means pressing against one of said detents whereby said
eccentric pivot pin is prevented from rotating during normal operation of
said tool,
d) a control means on one end of said eccentric pivot pin whereby rotation
of said control means rotates said eccentric pivot pin.
18. The hand tool having first and second handles and first and second
jaws, at least one of said handles and jaws being pivotably connected,
each of said pivotably connected jaw and pivotably connected handle having
an adjustable mechanism, said adjustable mechanism comprising:
a) an eccentric pivot pin having an eccentric circular cross section in the
middle of said eccentric pivot pin and having an inline circular cross
section at one end, said eccentric pivot pin having an enlarged head with
a plurality of detents thereon at the other end, said eccentric circular
cross section contacting a first load transferring member, said inline
circular cross section contacting a second load transferring member,
b) a locking means securing said eccentric pivot pin from moving axially,
c) a pressure means pressing against one of said detents whereby said
eccentric pivot pin is prevented from rotating during normal operation of
said tool,
d) a control means on one end of said eccentric pivot pin whereby rotation
of said control means rotates said eccentric pivot pin.
19. An adjustable mechanism for tools having at least one moveable blade or
jaw including a load transferring means securing the moveable members
together, at least one moveable handle to transfer power to the tool, said
adjustable mechanism comprising:
a) an eccentric pivot pin having an eccentric circular cross section in the
middle of said eccentric pivot pin and having an in-line circular cross
section at one end, said eccentric pivot pin having a polygonal head at an
opposed end, said polygonal head having a plurality of flat surfaces
formed thereon, said eccentric circular cross section contacting a first
load transferring member, said in-line circular cross section transferring
a second load transferring member,
b) a locking means securing said eccentric pivot pin from moving axially,
c) a pressure means comprising a spring member exerting a force on one of
said flat surfaces of said polygonal head whereby said eccentric pivot pin
is prevented from rotating during normal operation of said tool, and
d) a control means on one end of said eccentric pivot pin whereby rotation
of said control means rotates said eccentric pivot pin, the force exerted
on one of said faces of said polygonal head being sufficiently low to
permit rotation of said eccentric pivot pin by rotation of said control
means.
Description
FIELD OF THE INVENTION
The present invention relates to the design and construction of adjustment
mechanisms commonly employed in hand tools which create compressive forces
between their blades or jaws. This includes crimping tools, swaging tools,
and bolt cutters. Mechanisms which adjust the position of the blades or
jaws have been used with medium and heavy duty hand tools for many
decades. These mechanisms allow the operator to adjust the final
positioning of the jaws and thereby control parameters such as peak force
and crimp size.
A second function of the adjustment mechanism is the compensation for wear
occurring in the components of the tool. As the blades, jaws, or pivot
pins wear, it is necessary to adjust for this wear. Without adjustment,
the worn tool would either fail to close properly and the tool's
performance would suffer.
Adjusting mechanisms also permit the use of multiple strokes with the tool.
For example, after an initial crimping, the operator could rotate the
eccentric pin and perform a second crimping to crimp even more.
DESCRIPTION OF THE PRIOR ART
The present invention is concerned with medium and heavy duty tools. These
types of tools generally include a compound lever system that creates a
maximum force at or near full closure of the blades or jaws.
Light duty hand tools do not need much adjustment because they do not use a
compound lever system. Compound lever systems do not work properly when
components are worn because it is necessary to create a maximum force at
or near full closure. It has therefore been a common feature of medium and
heavy duty hand tools, such as bolts cutters and swagging tools, to
incorporate adjustment mechanisms into the tool.
Many previous adjustment mechanisms have been designed for medium and light
duty applications and are not suitable for heavy duty tools such as U.S.
Pat. No. 3,733,626 by Irvin Allen and U.S. Pat. No. 5,012,666 by Ching Wen
Chem.
U.S. Pat. No. 5,063,770 by Ching Wen Chem and U.S. Pat. No. 5,067,370 by
Joseph Lemmens are examples of mechanisms which are not quickly
adjustable. These mechanisms require multiple steps to adjust.
Other current designs have complex, multi-part adjustment mechanisms which
require elaborate operations to adjust. These mechanism use an adjustable
bar held to the handle by a pivot pin and a locking bolt. In addition, two
hex head screws are used to adjust the bar, indirectly adjusting the
position of the blade of the tool at full closure position. This system is
both extremely complex and difficult to adjust because of the small size
of the hex head screws. These screws adjust the blade position in a
nonlinear manner and often corrode and break under normal use.
U.S. Pat. No. 5,012,666 by Chen et al. describes a system which adjusts the
distance between two of the pivot points on the tool. This system involves
many moving parts which are under high stresses. The adjustment system is
also easy to adjust accidentally during normal use.
None of these designs and mechanisms allow the operator to precisely and
quickly adjust the position of the jaw in heavy duty hand tools. Therefore
there is a need for a simple, reliable and low cost adjusting mechanism
with precise adjustments, incremental wear compensation and good
reliability.
OBJECTS AND ADVANTAGES
The primary object and advantage of the present invention is to provide an
adjustable control mechanism for hand tools and table production tools
which provides the operator with the capability to easily adjust the final
blade or jaw position. This allows the operator to quickly adjust the tool
when the tool components have worn and the tool cannot operate optimally.
A second object of the invention is to permit the use multiple strokes with
the tool. For example, after an initial crimping, the user could rotate
the eccentric pin and perform a second crimping to crimp even more.
Another advantage of the invention is the ease in which the system can be
adjusted. The pressure pin mechanism resists the motion of the eccentric
pin during normal use. When enough force is applied to the eccentric pin,
the pressure pin will allow it to rotate. The entire operation can be
performed with a partial turn of a wrench. The use of a control lever or
handwheel on the eccentric pin would allow even faster adjustment. Current
mechanisms in production require wrenches or keys to adjust.
Another advantage of this invention is that it can be easily incorporated
into current tool design. The eccentric pin assembly can replace any pivot
pin currently on a tool. Components such as handles, blades, jaws, and
plates could remain the same.
A further object of the invention is to provide a design which can be
manufactured easily. The main components can easily be manufactured using
automatic processes such as an automatic lathe for the eccentric pin and
injection die casting for the lever and control. This allows the proposed
design to be manufactured easily and inexpensively.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a shows a top view of an adjustment mechanism for hand tools in
accordance with the first embodiment of the invention (as part of a
compression tool).
FIG. 1b shows a cross-sectional view following line 1--1 of FIG. 1a of the
adjustment mechanism.
FIG. 1c shows an enlarged view of the adjustment mechanism of FIG. 1a.
FIG. 1d shows an alternative design of FIG. 1c.
FIG. 1e shows an alternative design of FIG. 1b in relation of the eccentric
pin.
FIG. 2a shows a top view of an adjustment mechanism for hand tools in
accordance with the second embodiment of the invention (as part of a bolt
cutter tool).
FIG. 2b shows a cross sectional view following line 2--2 of FIG. 2a of the
adjustment mechanism.
FIG. 2c shows an enlarged view of the adjustment mechanism of FIG. 2a.
FIG. 2d shows an alternative design of FIG. 2c.
FIG. 3a shows a top view of an adjustment mechanism for hand tools in
accordance with the third embodiment of the invention (as part of a swager
tool).
FIG. 3b shows a cross-sectional view following line 3--3 of FIG. 3a of the
adjustment mechanism.
FIG. 3c shows an enlarged view of the adjustment mechanism of FIG. 3a.
FIG. 3d shows an alternative design of FIG. 3c.
______________________________________
Reference Numerals in Drawings
______________________________________
FIG. 1
10 blades 12 compression surfaces
14 blade bolts 16 plates
18 handle 20 handle
21 handle bolt 22 handle bolt
24 square eccentric pivot pin
26 large circular hole
27 shoulder head of pivot pin
28 pressure pin
30 spring 32 adjusting screw
34 threaded hole 35 medium hole
36 eccentric segment of pivot
38 Allen surface
pin
40 C-clip 42 small hole
44 square head flat surface
46 (0) minimum
48 pointer 50 (3) maximum
52 hexagonal eccentric pivot
53 hexagonal head flat surface
pin
54 Allen screw 56 eccentric pivot pin
57 adjusting knob 58 mating surface
FIG. 2
60 stopper pin 61 stopper pin hole
62 cutting surface 64 blade
66 blade 68 handle
70 handle 72 central bolt
74 eccentric pivot pin
76 rounded corner adjusting head
78 set screw 80 threaded hole
82 large circular hole
84 small hole
86 eccentric segment
88 C-clip
92 Allen screw 94 hexagonal pivot pin
FIG. 3
100 compression holes
102 blade
104 blade 106 handle
108 eccentric pivot bolt
110 rounded corner square head
112 knob 116 small hole
118 large quasi circular hole
120 shoulder head
122 friction washer 126 threaded segment
128 nylon lock 139 eccentric segment
132 medium hole 134 rounded pockets (2)
136 pointer 138 (0) minimum
140 (3) maximum 142 large quasi-circular hole
144 rounded hexagonal pivot
146 rounded pockets (4)
bolt
______________________________________
SUMMARY OF THE INVENTION
The present adjustment mechanism for hand tools consists of an eccentric
pin located at one of the pivot connections on a tool. For instance, the
eccentric pin can be placed in between the handles or at the connection of
the handle to the tool blades. The eccentric pin controls the relative
spacing between two of the tools moving components. This indirectly
controls the final positioning of the tool blades or jaws
The eccentric pin mechanism can be placed at any pivot on the tool. The
strength of the eccentric pin design allows it to be used at pivots
carrying even the highest loads. Placing the pin at the highest stressed
pivots would allow a small adjustment of the eccentric pin to provide a
similar adjustment in the blade or jaw position.
A pressure pin mechanism presses on the eccentric pin head and resists the
rotation of the eccentric pin. The pressure pin mechanism can be designed
to allow the operator to rotate the eccentric pin with or without the use
of tools, while preventing the pin from rotating during normal
Periodic adjustment of the tool can be done easily and precisely since each
step adjustment of the eccentric pin adjusts the tool a finite amount. The
maximum number of adjusting steps can only be realized if the pin is
rotated in alternate directions during each adjustment. If the eccentric
pin is adjusted in only one direction, only one half of a revolution can
be used and fewer adjustments will be realized. For example, a square head
pin will allow 2 adjustments, a hexagonal will give 3 adjustments, and an
octagonal pin 4 adjustments. Generally these steps adjustment will provide
between 0.005 inch and 0.020 inch adjustment of the blades or jaws.
DESCRIPTION--FIGS. 1 TO 3
The first embodiment of the adjustment mechanism of the present invention
is shown in FIG. 1A, incorporated in a compression tool. FIG. 1B gives a
cross-sectional view of this first embodiment of the adjustment mechanism,
along the section lines 1--1 in FIG. 1A. FIG. 1C gives an enlarged front
view of the adjustment mechanism. FIG. 1D shows an enlarged front view of
an alternative design of the adjustment mechanism. FIG. 1E gives a
cross-sectional view of an alternative design of the eccentric pivot pin.
The compression tool shown in FIG. 1A has two blades 10, with compression
surfaces 12, secured together by plates 16 and blade bolts 14. The blades
10 are operatively connected to handles 18 and 20 through handle bolts 21
and 22. Handles 18 and 20 are rotationally connected to a square eccentric
pivot pin 24. A pressure pin 28 is pushed against a square head flat
surface 44 by a spring 30. Spring 30 is compressed by an adjusting screw
32, which is located in a threaded hole 34 of handle 20.
The eccentric pivot pin 24 is the most important part of the adjustment
mechanism of the present invention, and is located at one of the pivot
points of the tool. The eccentric pivot pin is most readily incorporated
in a configuration such as that shown in cross-section in FIG. 1B, where
handle 20 has double walls and handle 18 has a central section between
these two walls. Such a configuration is customary in most medium and
heavy duty tools, but is also presently seen in some light duty tools. As
seen in FIG. 1B, the eccentric pivot pin 24 is housed in a large circular
hole 26 and a small hole 42 of handle 20; the eccentric segment 36 is
located in a medium hole 35 in the central section of handle 18. The size
of the small hole 42 is determined by the minimum strength required for
the pivot pin. The size of the medium hole 35 is dictated by the amount of
adjustment desired over the life of the tool or the number of step
adjustments desired. The diameter of the large circular hole 26 is
dictated by the size of the pivot pin used for the adjustment mechanism,
and must be at least as large as the sum of the small hole diameter plus
three times the eccentric variation of the pivot pin. FIG. 1B also shows
that the eccentric pivot pin 24 is axially secured by shoulder head 27 and
C-clip 40. Adjusting screw 32 holds spring 30 and pressure pin 28 in
threaded hole 34. Eccentric pivot pin 24 can be rotated by means of an
Allen surface 38.
An enlarged front view of the square eccentric pivot pin 24, as it would
appear removed from the mechanism, is given as FIG. 1C, showing details of
a pointer 48 and numeral position markers. The pivot pin can be
rotationally adjusted from a minimum at the numeral 0 shown as 46, to a
maximum at the numeral 3, shown as 50.
FIG. 1D shows an alternative design utilizing a hexagonal eccentric pivot
pin 52. In this alternative configuration of the adjustment mechanism, an
Allen screw 54 provides a stronger means of adjustment.
FIG. 1E shows a cross-sectional view of an alternative eccentric pivot pin
56. In this configuration, the end of the pivot pin supports an adjusting
knob 57 rotationally secured by a mating surface 58 and axially secured by
a C-clip as before. A stopper pin 60 limits the motion of the adjusting
knob 57. The use of an adjusting knob offers increased ease and speed of
adjustment. Knob 57 can be adjusted by 60 degrees if mating surface is a
hexagon or 30 degrees if mating surface is a 12 point surface.
Fabrication of eccentric pins 24, 52, and 56 is usually done through
machining of a square or hexagonal bar of carbon steel on a production
lathe or a CNC machine center, with an extra step for the Allen surface 38
or mating surface 58. The machining would be followed by a hardening and
tempering of the material, plus an anti-corrosion treatment. Other
components, such as C-clip 40, pressure pin 28, spring 30, adjusting screw
32, adjusting knob 57 and stopper pin 60 are all readily available
industrial components. The pressure pin, spring and screw are even
available as a single unit in various designs, sizes and strengths.
Assembly of this first embodiment of the adjustment mechanism can be
carried out in at least two different ways. In one method, the complete
tool can be assembled except for the eccentric pivot pin 24, which can
then be inserted through large circular hole 26, medium hole 35, and small
hole 42 and secured with C-clip 40. Proper positioning of the blades 10
and the handles 18 and 20 allows easy insertion of eccentric pivot pin 24.
The next steps are adjustment of the pointer 48 with an Allen key, and
insertion of pressure pin 28, spring 30, and screw 32. In a second method,
the two handles 18 and 20 can be assembled with eccentric pivot pin 24
prior to the assembly of the head of the tool.
Tool calibration should be done at one of the handle bolts 21 or 22 through
cutting at final size or clearance cutting during final assembly. This
will allow the eccentric pin rotation and pointer to be set with a minimum
at the numeral 0, and therefore allow the maximum number of adjustment
steps.
It may be helpful for fabrication of the eccentric pivot pin to include
information needed to determine the offset of the minimum eccentricity,
the alignment of the pointer in relation to the pivot pin 24 and the
handle bolts 21 and 22, and to calculate the adjustment steps giving best
variation of eccentricity between minimum and maximum. The offset
discussed here is defined at the fully closed position of the tool, and is
measured along a line from the eccentric pivot pin 24 to a handle bolt 22.
If an acceptable step variation for a hand tool is approximately 0.010",
then the maximum eccentricity would be less than 0.040" for the square
adjustment mechanism and less than 0.060" for the hexagonal adjustment
mechanism. To provide nearly equal variation for each adjustment step of
the eccentric pivot pin it is necessary to locate the minimum eccentricity
in an offset position in relation to pivot pin 24 and handle bolt 22. It
should be noted that if the minimum eccentricity were located toward bolt
22, the first two adjustment steps would provide the same degree of
eccentricity and one or two potential adjustment step would be lost.
Approximately equal variation of eccentricity with each adjustment step for
the square eccentric pivot pin will be achieved with a 17.5 degree offset
when the 0 position lines up with bolt 22, and with equal steps of 45
degrees. Since eccentricity does not differentiate between positive and
negative angles, the recommended steps are: 0=-17.5; 1=62.5; 2=-107.5;
3=152.5. Similarly, to provide the best variation of eccentricity from
minimum to maximum with the hexagonal eccentric pivot pin, an offset of 15
degrees is required at the 0 position, and the variation between steps
will be 30 degrees. The steps will therefore be: 0=-15; 1=45; 2=-75;
3=105; 4=-135; 5=165.
A second embodiment of the present invention provides a direct locking of
the adjustment mechanism and is thus well-suited to heavy-duty hand tools
such as the bolt-cutting tool shown in FIG. 2A. A cross-section of the
adjustment mechanism is shown in FIG. 2B, following the section lines 2--2
in FIG. 2A. An enlarged front view of the adjustment mechanism is shown in
FIG. 2C, with an alternative design of the eccentric pivot pin presented
in FIG. 2D.
The bolt-cutting tool in FIG. 2A has cutting surfaces 62 on blades 64 and
66, which are held together by plates 16 and blade bolts 14. Blade 64 is
connected to a handle 68 by a handle bolt 21. The two handles 68 and 70
are connected by a central bolt 72. Blade 66 is connected to a handle 70
by an eccentric pivot pin 74. The eccentricity of pivot pin 74 is set
through rotation of an adjusting head 76. A set screw 78 in a threaded
hole 80 locks pivot pin 74 in the chosen position.
The mechanism of the eccentric pivot pin 74 is shown more clearly in the
cross-sectional view of FIG. 2B. The pivot pin 74 is housed in a large
circular hole 82 and a small hole 84 in the two walls of handle 70; the
eccentric segment 86 is located in a medium hole in blade 66. The pivot
pin is axially secured by shoulder head 27 and C-clip 88.
FIG. 2C shows in more detail the front view of the pivot pin 74 with
eccentric segment 86, rounded corner adjusting head 76, pointer and
numeral markers. FIG. 2D shows an alternative hexagonal pin 94, which has
many of the same features as the eccentric pivot pin 74, but provides more
adjustment positions. In this design, the set screw 78 is replaced by an
Allen screw 92 to provide a higher locking force.
A third embodiment of the adjustment mechanism incorporates a knob for the
rotational adjustment rather than requiring an Allen wrench. This
embodiment is shown in FIG. 3A, incorporated into a swaging tool. A
cross-section of the adjustment mechanism is shown in FIG. 3B, following
the section lines 3--3 in FIG. 3A. A cross-section of the eccentric pivot
bolt is shown in FIG. 3C, following the section lines 4--4 in FIG. 3B. An
alternative bolt design is presented in a similar cross-section in FIG.
3D.
The swaging tool in FIG. 3A has several sizes of compression holes 100 on
blades 102 and 104, which are held together by plates 16 and blade bolts
14. Blade 102 is connected to handle 68 by handle bolt 22. The two handles
68 and 106 are connected by a central bolt 72. Blade 104 is connected to
handle 106 by eccentric pivot bolt 108. The positioning of the eccentric
pivot bolt is facilitated by a pointer 136 and numeral markers, such as
the marker for a minimum at the numeral 0, shown as 138, and a maximum at
the numeral 3, shown as 140.
The mechanism of the eccentric pivot bolt 108 is seen more clearly in
cross-sectional view of FIG. 3B. The eccentric control bolt 108 is housed
in a large quasi-circular hole 118 and a small hole 116 in the two walls
of handle 106. The eccentric segment 130 is located in a medium hole 132
in blade 104. The eccentric pivot bolt 108 is axially secured on one side
by a shoulder head 120. The bolt is secured on the other side by a
friction washer 122 and an adjusting knob 112 screwed onto a threaded
segment 126 of eccentric bolt 108. Controlled torque applied to knob 112
is done through a rounded corner square head 110.
FIG. 3C is a cross-section of the eccentric bolt in which the details of a
rounded corner square head 110 and its locking capability into a
quasi-circular hole 118 can be seen. The hole 118 has two matching rounded
pockets 134 for clearance which prevent the eccentric bolt 108 from
rotating under radial load. Under conditions of no load or low load the
friction washer 122 prevents rotation of bolt 108. This double friction
system allows easy positioning of the eccentric segment 130 via knob 112,
while preventing rotation during high load operation.
Since the rounded corner square head 110 of bolt 108 is a few thousandths
of an inch smaller than the minimum diameter of the large quasi-circular
hole 118, rotational motion is allowed. However, the increased diameter at
the rounded pockets 134, although very small, acts like a meshing gear
under load and thus prevents rotation during operation. It should be noted
that the rotational torque received by bolt 108 during operation is
usually about equal between the large and small holes of handle 106 and
the medium hole 132 of blade 104. The intrinsic self-power loading
characteristic of the eccentric bolt through its rounded square section
makes it capable of holding even high torque.
FIG. 3D shows an alternative design of the eccentric pivot bolt in which
the contacting surfaces are a rounded hexagonal pivot bolt 144, with four
rounded pockets 146, and the large quasi-circular hole 142.
The order of assembly of the second and third embodiments is similar to
that of the first embodiment.
From the description above, a few of the advantages of my invention of an
adjustment mechanism for hand tools become evident. In the operation of a
hand tool such as a compression tool, bolt cutter, swaging tool and the
like, it is frequently necessary for the user to make adjustments to the
tool closure to reduce the size of the stroke either for wear compensation
or stroke control; or to reduce the size of the tool so that two power
strokes will achieve the intended result. My invention offers a low cost,
compact, convenient, effective and reliable control adjustment for hand
tools for many commercial and industrial uses.
OPERATION
The adjustment mechanism is utilized when it is desired to adjust the size
of the stroke. In the preferred embodiment of the present invention, as
shown in FIG. 1A, a square eccentric pivot pin 24, located at a pivot
point of two handles 18 and 20, allows the user of the hand tool to vary
the maximum distance that blade bolts 14 will move apart during full
closure of the handles. This distance will determine how far the
compression surfaces 12 of the blades 10 will close. As best seen in FIG.
1C, as it would appear removed from the mechanism, the eccentric pivot pin
has four positions; a position is selected by the user using an Allen key
in the Allen surface 38 to rotate the eccentric pivot pin. The pointer 48
is rotated to a higher numeral marker, up to the maximum numeral 3, shown
as 50, to increase the total compression; or to a lower numeral marker,
down to the minimum numeral 0, shown as 46, to reduce the total
compression. The pressure pin 28, pushed against the square head flat
surface 44 by a spring 30 compressed by an adjusting screw 32, maintains
the position of the eccentric pivot pin during normal use of the tool, but
does allow rotation of the pivot pin under a sufficient torque.
The hexagonal eccentric pivot pin shown in FIG. 1D differs in having five
rotational adjustment positions rather than three. Also, the adjusting
screw 54 that determines the pressure of the pin on the hexagonal head
flat surface 52 is now an Allen screw.
In the alternative design shown in FIG. 1E, an adjusting knob 57 is used to
select a position of the pivot pin. The knob allows the user to adjust the
stroke more quickly and easily without the need for an Allen wrench. A
stopper 60 limits the rotation of the knob 57.
A second embodiment of the present invention, shown in FIG. 2, has an
eccentric pivot pin 74 that is locked directly by a set screw 78.
Adjustment of the pivot pin is achieved by loosening the set screw 78,
rotating the rounded corner adjusting head 76, and relocking screw 78.
This procedure provides a direct locking of the adjustment mechanism
suited to heavy-duty applications where frequent adjustment is not
necessary.
In a third embodiment of the present invention, shown in FIGS. 3, the
position of the eccentric pivot bolt 108 is adjusted by means of a knob
112, and marked by a pointer 136 and numerals from a minimum of 0, shown
as 138, to a maximum of 3, shown as 140. The position is held with
precision by a combination of a friction washer 122 and shoulder head 120.
Initial tightening of the knob 112 is accomplished by holding the rounded
corner square head 110 with an open wrench while rotating knob 112.
CONCLUSIONS AND RAMIFICATIONS
The adjustable mechanism for hand tools presented here offers many
advantages over current mechanisms. The adjustable eccentric pin is both
easily adjusted and easily manufactured. The eccentric pin is also capable
of withstanding the high loads associated with heavy duty hand tools such
as bolt cutters, swaggers, and crimping tools.
It should be noted that the present invention should not be restricted to
any particular arrangement or any specific embodiment disclosed herein.
The present invention should also not be limited to any specific tool. The
adjustable mechanism presented here could be used on equipment ranging
from bolt cutters and swaging tools to table production tools. The high
load carrying capacity of the presented mechanism allows the mechanism to
be used on any tool.
Many of the components in this invention can be altered while still
performing the same function. For example, the spring and adjusting screw
retaining the eccentric pin could be replaced with a single screw
constructed out of a resilient material such as nylon. A nylon screw with
a steel head could be alternately used. Another means of preventing the
rotation of the eccentric pivot pin could be the use of a spring loaded
wire abutting against the side of the eccentric pin head.
The adjusting knob on the eccentric pin could be located at either the
front of rear of the tool. Also, several of the shapes of matching
components could be changed and still operate in a similar fashion. Thus
the scope of the invention should be determined by the appended claims and
their legal equivalents rather than by the examples given.
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